MUMBAI, India (CNN) -- The Indian city of Mumbai exploded into chaos late Wednesday as gunmen launched a series of attacks across the country's commercial capital, killing scores of people and taking hostages in two luxury hotels frequented by Westerners.

CNN correspondent Andrew Stevens was on assignment in Mumbai when the attacks began.

He talks with CNN's Miles O'Brien about the scene on the ground.

O'Brien: This is a city that is paralyzed right now. Andrew, set the scene for us.

Stevens: Miles, for the last three hours, this has been a city becoming increasingly in lockdown. We are still in the middle of an ongoing situation; we cannot say yet just how big the scale of this is.

There have been, as you say, multiple attacks on multiple targets.

At the moment, there is a hostage situation in both of these five-star hotels, the Taj Palace Hotel, which is probably the best-known hotel in Mumbai, and the Oberoi Hotel, which is only a five minute drive away from the Taj.

What we've been hearing and what I have heard from an eyewitness interviewed on local TV here, he said he was in the Taj when he saw two gunmen going down into the lobby where there were guests. They rounded up some 15 people, 15 hotel guests, he said they were asking anyone whether anyone had British and American passports. He said several were taken hostages.

He could not give a number, and I want to repeat, I cannot personally confirm this. We have not been told this by authorities but that's what is being told on air at the moment.

There is a hostage situation in the Taj -- we're also being told there are gunmen on the roof of that hotel lobbing hand grenades at anti-terror operatives on the ground. Five minutes away at Oberoi Hotel, there's also a hostage situation.

We have fewer details about that at the moment, but there are also reports coming in that there may have been firing in another hotel in another part of the city, so we don't know if this is confined to the southern area of Mumbai, where I am, or if it's actually spreading out across the city.

I spoke to an eyewitness in the Taj hotel just about five minutes ago, and he said everything had been dead quiet for the last hour or so. But he's sitting in his room, the lights are off there, there's no TV, no communication. He was just told by front desk to stay put and they will advise him. Watch Stevens describe the scene on the ground »

O'Brien: At this point, we're hearing reports of possibly seven locations targeted. Do those numbers jive with what you're hearing on the ground?

Stevens: Yes that's right, three hotels; those two I mentioned, another hotel, the Ramada in the north of the city; the hospital, the Central Railway Station, which is a place where hundreds of thousands of people travel day and night. A very busy busy place. The Leopold Café, which is a very popular tourist café very close to the Taj as well and also.

International hot lines

Australia: The Department of Foreign Affairs and Trade has set up a hotline for Australians with concerns for family or friends in Mumbai: 1800 002 214U.S.: The State Department has established a Consular Call Center: 888-407-4747. UK: Foreign Affairs Ministry: 44 (0) 20 7008 0000

We're also hearing reports from the domestic airport that there may have been an explosion there in or underneath a taxi, so around about seven at this stage.

O'Brien: Including the airport, is there some concern about additional activity, additional hostage-taking or attacks and what do we know about that?

Stevens: Because the situation hasn't been brought under control, there's a huge amount of concern about what could happen next. Security is being ramped up across the city at the moment, also the government says it has dispatched some 200 commandoes, and just a few minutes ago there were pictures that showed the commandoes arriving around the Oberoi Hotel.

Both the navy and army were put on alert, says the government, but not actually activated.

O'Brien: If you can help us understand, it's now 2 or 3 in the morning, on a typical day, midweek. How many Westerners would there be in that city?

Stevens: It's difficult to say, but I have been staying at the Taj, CNN has had a crew in Mumbai all week, at least half the guests would be Westerners, and I'm pretty sure it would be the same at the Oberoi.

Mumbai is the commercial capital of India, and as you know, India is booming at the moment, so there is a lot of international business in Mumbai. The Taj and the Oberoi are at the top of the list for anyone doing business here.